Apparatus for treating liquids with gases



W. E. GREENAWALT.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

APPLICATION FILED NOV-4, 1919.

Patented Apr. 12, 1921.

3 SHEETS-SHEET 1- FIG 2 INVENTOR @wm m W. E. GREENAWALT.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

APPLICAIION FILED NOV. 4.1919

Patented Apr. 12, 1921.

3 SHEET$-SHEET 2.

.Tanli INYENTOR I I? W. E. GREENAWALT.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

' APPLICAIION FILED NOV. 4,1919. I 1,3?4,Q45 Patented Apr. 12, 19211.

3 SHEETS-SHEET 3.

3'0 finely subdivided, or atomized, in the liquid.

WILLIAM E. GREENAWAL'I, OF DENVER, COLORADO.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

Specification of Letters Patent. kPatented A 12 1921 I I Application filed November 4, 1919.- Serial No. 335,760.

T all whom it may concern:

Be it known that I, WILLIAM E. GREENA- WALT, a citizen of the United States, residing in the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Apparatus for Treating Liquids with Gases, of which the following is a specification.

The invention has forits object the effective application of gases to liquids to accompli'shcertain results, such, for example, as the precipitation of metals from their solutions by a gaseous precipitant, bringing metals into solution by means of-a gaseous reagent, and the treatment of finely ground ores by flotation on the addition of a suitable flotation agent. It is not intended to limit it to any particular use, although in describing the app 'ratus the flotation treatment of ores will be kept more or less in mind. I

This application may be regarded as a modification or improvement of that described in may co-pending applications, Serial No. 58,748, filed October 30,1915, and Serial No. 68,718, filed December 27, 1915, and

Serial No. 845,011, filed June 13, 1914.

The best results in the flotation treatment of ores of metals, under assumed conditions, are obtalned when the a1r, or other'gas, 1s

It may be said that the results are more or less proportional to the extent to which the gas is atomized. In subaerating flotation machines in which the air is broken up by rapidly rotatingpaddles, the atomization is not effectively accomplished, either as to the fineness of thesubdivision, or as to the power consumption. In consequence, there is not obtainable either the highest grade concentrate or the highest possible extraction of the: mineral from the gangue.

In the present invention, as in my copending applications referred to, extremely effective subdivision of the gas is accomplished by passing the gas through ducts, or gas passages, in an atomizer submerged in the liquid and rotating the atomizer at a high speed.

In my co-pending applications referred to, the as is preferably introduced into the liquid rom a stationary gas outlet and delivered into the interior of the atomizer, and .ejected into the liquid in the tank either by the pressure of the liquid on the gas, or

by the centrifugal action of the atomizer.

This method is preferred in most instances because it admits of easy regulation of the gas within wide limits, and this regulation, in some types of machines, is quite essential for obtaining both a high grade concentrate and a high percentage of extraction. In the apparatus referred to, it is possible to eject only gas through the gas passages, or

only liquid? or both, 'as desired, dependlng, usually, upon theamount of air used.

It is not always convenient, however, to supply the gas by means of a compressor. The gas may be supplied to the atomizer through a hollow shaft by the suction induced by the atomizer. Much the'best-results are usually obtained by ejecting a mixture of gas and liquid through the gas passhows a cross-section of the apparatus.

Fig. 2, a longitudinal section: Fig.3, a de tail'of the atomizer in ideal vertical section; and Fig. 4, the corresponding horizontal section on the line 44 of Fig. 3. Fig. 5, a' detail of a modified atomizer in ideal vertical section, and Fig. 6, the corresponding horizontal section on the line 6-6 of F1g.

5. Fig. 7, is another modified atomizer in ideal vertical section, and Fig. 8, is a horizontal section on the line 88 ofFig. 7, and Fig. 9, a horizontal section on the line 9-9 of Fig. 7.

In the drawings, 1 is a tank adapted to contain a liquid and the material to be treated'; 2 is a hollow shaft vertically mounted in the bearings 3; 4 is an atomizer, suspended within the tank and submerged in the liquid, which, when rotated at a high speed,

(gas, in the liquid, 'by

atomiz'es the air, or ejecting the gas, mixe with a portion of the liquid,'through the passages 5. The shaft may be belt driven by means of the pulley 6. The speed at which the shaft is rotated Wlll ordinarily vary from 250 to 1000 R. P. M.,

to get the best results. The degree of atom-' ization of the gas, 1 under assumed conditions, will depend almost entirely on the speed of rotation. A little experimenting.

smoothexterior surface so that when the atomizer is rotated at a high speed the friction with the liquid will not be excessive and the agitation reduced to a minimum. The

. atomizer is provided with gas passages 5 extending, preferably, from its interior central portion toward the periphery. These gas passages communicate with the atmosphere abovethe liquid through the hollow shaft 2, and with the liquid in the tank through the aperture in the plug 7, so that whenthe atomizer'is rotated with'suflicient speed both air and liquid may be ejected through the gas passages. It is evident, also, that if the aperture in the plug-7 is suificiently large, liquid would be ejected to the exclusion of the air. To overcome this difliculty the plugs are made with different sized apertures' A little experimenting will determine the best plug to use. The

' idea is toconstrict the opening in the plug so that the suction in the gas passages will also be suflicient to cause a flow of both gas and liquid through the gas passages. Having determined on the plug with the most suitable aperture for the conditions of speed of rotation of the atomizer and the depth of the atomizer in the liquid, the inflow of air can be regulated by the valve 8, above the opening in the shaft. This valve may be in the nature of a plate or disk 8 mounted on the pipe 9, a portion of which, 19, is threaded. By turning the disk on the stationary pipe 9, any desired regulation of air may be obtained, and by having a series of lugs with different size apertures any desired proportion of air and liquid may be obtained and ejected through the gas passa es.

ithin the central portion of the atomizer 4 are cross pieces 10 which rotate with the atomizer and thoroughly mix and distribute the gas and liquid before it is ejected through the gas passages 5. Much of the effectiveness of the aeration depends on the proper ejecting of a mixture of air or gas andthe liquid. It is difficult to effeet a thorough mixture after the air or gas has once been ejected through the gas passages into the liquid. The ejecting of a*' mixture of gas and liquid also gives a better distribution of the atomized gas in the liquid in the tank than when the gas is ejected alone through the gas passages.

It is frequently .desirable to introduce other substances besides air and liquid into theatomizer. If the substance is a liquid,

' as for example a flotation agent, it may be put into the small tank 11 above the holtail in Figs. 3 and low shaft and, by means of the stationary pipe 9, introduced into the central portion to be used, such for example as sulfur dioxid,

ammonia, or a vaporized flotation agent, it may be introduced through the pipe 12 and through the aperture in the plug 7, and its flow may be regulated by the valve 13. The

pipe outlet is stationary, and the gas once delivered to the'atomizer or into the liquid in the tank, is forced by the pressure of the liquid, and'by the suction of the atomizer, into the central portion of the atomizer and ejected with the mixture of air and liquid. If desired the gas could be introduced through the stationary pipe 9 in the hollow shaft, through the pipe 14, as shown in de- It is evident that air, as well as any other fluid, may be introduced through the pipe 14;, and this may be desirable in the event that the submergence of the atomizer is too deep or the rotary speed too slow to create suflicient suction to cause a flow of air through the hollow shaft.

Referring now'more particularly, to Figs.

1 and 2, the application of the invention to the flotation treatment of ores will be described. The ore pulp is delivered to the box 18 and flowed in tothe first compartment, or 'cell, of the twoseries, back to back, of fivecells each. The atomizers, driven at a rotary speed of from 250 to 1000 R. P.

M. cause a flow of air andliquid into the I interior central portion of the atomizers, and the mixture of air and liquid is ejected through the gas passages into the liquid in the tank. In this way the gas is finely subdivided or atomized) in the liquid. The flotation agent is placed in the tank 11 and is introduced into the iatomizer through the pipe 9 in the hollpw' shaft and its amount is regulated by the valve 29. If some other gas besides air is to be used, it

is introduced into the atomizer through the pipe 12 or the pipe" 14 and its amount regulated as desired.

In order to insure a thorough distribution of the atomized gas and to maintain a quiescent surface of the liquid, baffles, 15,

are placed in proximity to the atomizers.

A screen 16 may be placed on top of the baflies to further insure quiescence. The

tops of the baflies are kept below the surface of the liquid and the bottoms of the bafiies some distance above the bottom of the cells.

The pulp flows from one cell to the next of the series through the openings 17, at or near the lower portion of the cells. There is, preferably, no other liquid connection between the cells.

When the ore pulp 1s introduced into the first cell of the series, some of the mineral froth is floatedto the surface of the liquid and overflows into the froth launder 19. The tailings .from the first cell are passed into the next through the opening. 17 and their passage is facilitated by the rotary motion of the pulp in the lower portion of the cells,

below the baffles If it were not for this.

rotary motion of the liquid'in the lower portion of the cell there might be danger of clogging due .to the-rapid settling of coarse tailings in a quiescent liquid. The tailings from the first cell are given a further treatment in the second, and from the second in the third, and so on for the entire series of cells. The pulp is then wasted through the outlet 20. This outlet is arranged with a valve 21 to take a. portion of the flow containing the coarser material, and an overflow 22 by means of which the height of the liquid in the'tank, or in the entire series of cells, may be regulated at will. The openings' between the cells are intended to be large enough so that there will be no appreciable difference in the liquid level of the various cells due to the rotary atomizers. Skimmers 23 may be used to assist in removing the mineral froth from the surface of the li uid.

anifestly, by the arrangement in this apparatus, any particle of mineral which has a tendency to float will be floated above the level of the atomizers, while the tailings which have no mineral particles attached and have no considerable tendency to float are worked very quickly through the entire series ofcells. It will be observed that in this apparatus a mineral particle once floated cannot escape without first descending against the ascending hi hly atomized gas, to the openings 17 and tie outlet 20. The entire tendency is to keep mineral particles which have a tendency to float in the apparatus aslong as possible, and expel the totally barren gangue as quickly as possible. It is possible also, to get various floating conditions in the different cells by varying the speed of rotation of the. atomizers which can be done'by having various size pulleys on the main driving shaft, (not shown). The mixture'of gas and liquid may also be varied in the different cells, as also the flotation agent, or gas other than air introduced throughthe pipe 12.

Referring to Figs. 7, 8 and9, which show.

a modified form ofatomizer, the gas flows into the interior of the atomizer through the hollow shaft 2. The atomizer has two sets of passages extending from its-interior totroduced through the passages 25 are ejected into thebody of the liquid in the tank. The passages25 are preferably inclined toward the direction of rotation of the atomizer, as shown in Fig.8, in order to cause a pressure of liquid inwardly, and the passages 5, as

shown in Fig. 9, are preferably inclined away from the direction of rotation of the atomizer in order to eject the liquid and.

gases from the interior ofthe atomizer outwardly into the liquid in the tank and also create a suction inwardly through the-hollow shaft. The liquid inlets 25, as shown in Figs. 7 and 8, are restricted in area the same as the inletsshown in Figs. 3 and 5,

in order that gas may be sucked through the I hollow shaft and in order that gas and liquid may be ejected through the passages 5.

I claim:

1. In apparatus for treating liquids with gases, a tank adapted to contain a liquid,

' a rotary atomizer having gas'passages extend-- ing from itscentral portion toward its periphery suspended within the tank and submerged in the liquid, means for causing a flow of gas to the central portion of the atomizer, means for causing a flow of liquid in the tank to the central portion of the atomizer, rotary means for mixing the gas andthe liquid, means for ejecting the mixture of gas and liquid through the gas passages I of the atomizer from its "central portion toward the periphery and into the liquid in.

the tank, and means for rotating the atomizer about its vertical axis.

- 2. In apparatus for treating liquids with gases, a tank adapted to contain the liquid,

a rotary atomizer having gas passages extending from its interior toward its exterlor suspended within the tank' and submerged inthe liquid, means for causing a flow of gas toward the interior of the atomizer,

' means for causing a-flow of liquid in the tank toward the interior of the atomizer, rotary means for mixing the gas and liquid, means for ejecting'themixture of gas and liquid through the gas passages of the atomizer from the interior toward the exterior and into the liquid in the tank,-and means for rotating the atomizer about its vertical axis.

3. In apparatus for treating liquids with gases, a tank adapted to contain the liquid,

a rotary atomizer having gas passages extending from its central portion toward its periphery suspended within the tank and submerged in the liquid, a hollow shaft communicatin with the atmosphere above the liquid -an w1th the gas passages of the v rotary atomizer havin atomizer a stationary pipe passing through the hollow shaft with its outlet in proximity to the central portion of the atomizer, and means for rotating the atomizer about its vertical axis.

4. In apparatus for treating liquids with gases, a tank adapted to contain a liquid, a rotary atomizer having gas passages extending from its interior/toward its exterior suspended within the tank and submerged in the liquid, a hollow shaft communicating with the atmosphere above the liquid and with the gas passages of the atomizer, a stationary p pe extending downwardly within the hollow shaft with its outlet extending below the normal surface of the liquid in the tank, and means for rotating the atomizer about its vertical axis.-

5. In apparatus for treating liquids with gases, a tank adapted tocontaina liquid, a

gas passages extending from its centra portion toward its periphery suspended within the tank and submerged inthe liquid, a hollow shaft communicating with the gas passa es of the atomizer, astationary pipe exten ing downwardly within the hollow shaft and arranged for introducing a fluid substance through the stationary pipe and delivering it to the atomizer and ejecting it with the gas through the gas passages into the liquid in the tank, and means for rotating the atomizer about its vertical axis.

6. In apparatus for treating liquids with gases, a tank adapted to contain a liquid, an atomizer mounted on a hollow rotary member and communicating with the atmosphere above the liquid suspended within the tank and submerged in the liquid, said atomizer .having a set of passages extending from its interior toward its periphery and inclined toward the direction of rotation and re-" stricted in area so as to cause a flow of gas and l quid into the interlor of the atomizer, and another set of passages extending from its interior toward its periphery and inclmed away from the direction of rotation through which amixture of gas and liquid is ejected into the liquid in the tank. 7

7. In apparatus for treating liquids with ery and oppositely inclined inreference to the direction of rotation of the atomizer.

8. In apparatus for treating liquids with .gases, a tank adapted to contain a liquid, a

gas impregnator suspended within the tank and having its interior in c'ommunication with the liquid in the tank, means for causing a flow of liquid in the tank into the interior of the impregnator, means for causing a flow of gas into the interior of. the impregnator, rotary means in the interior of the impregnator for mixing the liquid and the gas, and'means for ejectin the mixture of liquid and gas into the liquid in the tank.

9. In apparatus for treating liquids with gases, a tank adapted to contain the liquid, a hollow rotary member having discharge passages in the walls thereof suspended within the tank and submerged in the liquid', a hollow shaft communicating with the interior'ofsaid rotary member, and a stationary pipe extendin downwardliy within the hollow shaft, an means for a mittlng a regulable quantity of as under pressure through the stationary pipe to the terior suspended within the tank and sub I I merged in the liquid, a hollow shaft communicating with the interior of the d1scharge passages of the rotary member, a stationary pipe passing through the hollow shaft with its outlet in the interior of said rotarymember, and'ineans for admitting a regulable quantity of fluid through the stationary pipe into the interior of said rotary member. 7

' 'W-ILLIA E. GREENAWALT. 

